From: Mike Lorrey (mlorrey@datamann.com)
Date: Sat Jul 13 2002 - 20:01:19 MDT
spike66 wrote:
>
> OK. Does anyone have the actual data for temperatures at the
> top of the dewar vs the bottom? I am surprised there is more
> than about a 5C delta.
Well, the N2 molecule is heavier than the H20 molecule (by nearly 2
times) so its pressure gradient should be similarly more steep. At those
temps, I'd not be surprised at a 5C delta top to bottom (note that the
N2 will be infused at the bottom, and rising as it absorbs heat from the
body, so that during the cooling process, you should easily attain a 5c
delta over a nearly 2 meter gradient. Since cooling the brain well and
fast is the primary objective, you want it to receive the coldest N2,
which it normally wouldn't if the body is upright, since the rising N2
currents would pass the torso, the largest heat mass of the body, before
reaching the brain in an upright corpsicle.
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